The Tykes sit fifth in the third tier having taken 27 points from their opening 15 games.
Neil Collins’ side are close on the heels of second-placed Oxford United in the automatic promotion places and only eight adrift of early league leaders Portsmouth.
The Yorkshire outfit are currently unbeaten in five in League One, but have won just one of their last four home fixtures at Oakwell.
The Hornets, meanwhile, have lost just once in their past 14 games in all competitions.
Horsham are seventh in the Isthmian Premier - just a point off the play-offs - and still in contention in the FA Cup, FA Trophy and Sussex Senior Cup.
Ahead of the tie at Oakwell, Di Paola admitted it would be a ‘massive undertaking’ for the Hornets to spring an FA Cup upset.
But the boss revealed he was busy formulating a game plan to produce arguably the biggest result in Horsham’s storied history.
Di Paola said: “You’re looking at what they do and you’re trying to give yourself the best chance to stay in the game.
"We have to be realistic - it’s going to be one of very few games this season where we’re not dominant on the ball.
“All the things we’re normally good at are not going to be happening at Barnsley.
"We have to come up with a bit of a game plan and an idea of how we want to attack what they do and respect their strengths, and then try and come up with a plan on how we can maybe cause them some problems.
“But we have to be realistic.
"There are five divisions between us.
"They’re a top team in that league. They’re having a great season, they play good football, they’re a good side with lots of qualities, so it’s going to be a massive undertaking to be honest.”
Watch out for coverage from Barnsley v Horsham on Friday night – and Worthing and Crawley Town’s Cup ties on Saturday – at sussexworld.co.uk/sport